Delayed arming device for a fuze



Jan. 27, 1959 R. WELLER DELAYED ARMING DEV-ICE FOR A FUZEV Filed June 3, 1949 ROYAL WELLER United States Patent DELAYED ARMING DEVICE FOR A FUZE Royal Weller, Silver Spring, Md., assignor to the United States of America as represented by the Secretary of the Navy Application June 3, 1949, Serial No. 97,064

Claims. (Cl. 102-79) (Granted under Title 35, U. S. Code (1952), sec. 266) a quantity of fluid within the projectile has attained a predetermined speed of rotation after the projectile has -been fired from a gun and the force of acceleration of the projectile has diminished to a value corresponding to the force of acceleration acting on the projectile at a safe distance from the gun after the` projectile has been tired therefrom. t

This invention provides new and improved means for preventing the premature explosion of the shell or projectile in or within the vicinity of a gun as the gun is red.

One of the objects of the present invention is the provision of new yand improved means for preventing the premature firing of an explosive charge within a projectile during the transportation, handling, loading and firing of the projectile froma gun. A j

Another of the objects is to provide new and improved means for maintaining the fuze in a `safe condition as the projectile is fired from a gun until the acceleration of the projectile `and the speed of rotation of a iluid sealed within a casing having the axis thereof in coincidence with the axis of the projectile has reached a predetermined value. i

Still anotherv object is to prov-ide a fuze for a projectile having new and improved mechanical means for delaying the arming of a` fuze as the projectile travels along a trajectory and to render the electricalvring mechanism effective when a quantity of fluid has caused movement of the arming mechanism in response to centrifugal force developed by rotationof the fluid.

A further object is to provide a new and improved fuze for an explosive projectile having `means arranged therein for preventing arming and ring thereof until the projectile is shot clear of the gun, which is economical to manufacture, reliable in operation, and which possesses thequalities of durability and safety during handling and transportation. v

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed., description when considered'in connection with the accompanying drawings wherein, Fig. 1 is a view partially in section of a projectile employing the fuze of the present invention according to a preferred embodiment thereof;

Fig. 2 is an enlarged sectional view of the fuze of Fig. 1 in an unarmed condition;

Fig. 3 is a diagrammatic view of the firing circuit therefor; and

Fig. 4 is a graph illustrating in diagrammatic form 2,870,714 Y Patented Jan. 27, 1959 the delay in the arming of the fuze caused by the retarded rate of acceleration of spin of the fluid within the expansible casing.

Referring now to the drawings for a more complete understanding of the invention and more particularly to Fig. 1 thereof, there is shown thereon a shell or projectile indicated by the numeral 10 comprising the shell casing 11 having the usual explosive or bursting charge 12 disposed therein, as is well known to those skilled in the art.

The fuze generally indicated by the reference charac ter 13, comprising a nose 14 is secured to the shell casing 11 in any suitable manner, preferably by an externally screw threaded nipple 18 having threaded engagement with shell casing 11. vThe nipple 18 is provided with an enlarged well 19, having a booster charge 24 arranged therein and composed of any explosive suitable for the purpose such, for example, as the type known in the trade as TetryL A reduced bore 25 is arranged within the nose 14 in communication with the well 19 and a lead-in explosive charge indicated by the reference character 26 is disposed therein, in engagement with the booster char-ge 24 to provide means for firing the booster charge when the fuze is functioned upon impact thereof with a target. The booster charge is sealed within the recess by a disc 27 composed of any material suitable for the purpose such, for example, as blotting paper or the like and Ia steel disc 31, the aforesaid discs being clamped in position by a flange 32 formed on the magazine and crimped or rolled into clamping engagement with disc 31.

The nose 14 has formed therein a recess or guide-way 33 having an arming plunger 34 releasably and slideably arranged therein. The arming plunger is urged to an armed position Fig. 2 by a spring 3S when the plunger has been released whereupon the sensitive detonator 36 disposed within a bore 37 -in the arming member is brought into registration with the lead-in charge 26. lt will be understood, however, that the arming plunger is locked in a safe or unarmed condition, Fig. l, by the usual centrifugally actuated detents (not shown), the detents being adapted to be moved to a release position in response to centrifugal force whereupon the plunger is moved to an armed position by the spring 35.

As shown on Fig. 2 the nose 14 is provided with a bore or passageway 38 comprising a vertical portion 39 and 'an inclined portion 40. The vertical portion is in communication with recess 33 and has disposed therein a sensitive detonator 41 in proximate spaced relation with respect to the plunger 34 and adapted to fire the detonator 36 when the plunger is in an armed position and upon impact of the shell with a target, The inclined portion is in communication with a centrally disposed bore 42 and has disposed therein a ash primer 43 adapted to be fired by a ring pin 44 releasably supported within the bore 42 by a shear pin 45 as the pin is severed upon `impact of the shell with a target.

Disposed within the inclined portion 40 of the bore 38 is a centrifugally actuated detent 46, the detent being normally urged into a safe position by a spring 47, Fig. 2, thereby to prevent communication between the bore 42 and the inclined bore 40 until the detent has been actuated to an armed position in response to centrifugal force. When this occurs the detent will be moved from the safe position sufficiently to permit communication between the aforesaid bores and thus permit the flash from primer 43 when fired by the tiring pin to contact and re the detonator 41.

The detent 46 is provided with a groove 48 having disposed therein one end of a pawl or latch 49, the other end thereof being rotatably supported on a pivot 51. The latch 49 maintains the detent 46 locked in a safe position l 3 untily actuated to a` releaseposition by the expansible bellows indicated generally by the numeral 53 as the bellows is extended to an armed position during the flight of the projectile: The bellows'53 is arranged within* a recess 52" formed in'thenose 14' with the axis thereof in coincidence with the spin axis of the projectile, the bellows comprising a pair of spaced end walls54 and 55 having respectivelyI secured thereto the endsof the expansible portion 56 thereof. The bellows has sealed therein a copious amount of liquid suitable for` the purpose such, for example, as oil, mercury; or the like.

-As shown in Fig. 2 the end wall 54 has formed thereon a boss 57. Secured to the boss 57 is a member 58 having formed thereon a lug 59 in engagement with the end portion 60 of the pawl 49. By means of this arrangement, the detent 46 is maintained immovable until the pawl is moved out of engagement therewith bythe bellows as the spin of the projectile gradually accelerates the liquid contained within the bellows which develops sufficient centrifugal force to cause the bellows to be lengthened or extended in response to such force. lt will be understood, however, that the transfer of angular momentum from the shell to the liquid will cause the liquid to develop sufficient centrifugal force to move the bellows gradually and longitudinally, the purpose of which motion will be more clearly apparent as the description proceeds.

When the fuze is in an armed position, the detonato:- 36 is in line with the lead-in charge 26 and also in line with the primer 41, the detent 46 having been moved outwardly sufficiently to permit an uninterrupted passageway between primers 43 and 41. Upon impact of the shell with a target the firing pin 44 is driven into firing engagement with the primer 41 with sufficient force to cause firing thereof, the flash therefrom being directed by way of passageway 38 into firing engagement with primer 41 and thus initiating firing of detonator 36, leadin charge 26 and booster charge 24 in successive order.

The electrical arming of the fuze is delayed by the specific construction and arrangement of the bellows 53 and the physicalf properties of the liquid sealed therein for the reason that as the projectile is fired from a gun and rotates about its axis the liquid within the bellows gradually accelerates rotatively, which acceleration develops sufficient centrifugal force to cause the liquid to be forced outwardly thereby creating sufficient pressure to extend the bellows.

As shown on Figs. 2 and 3 means are employed to arm the fuze by movement of the member 58 and to lire the fuze-electrically, if desired, the means comprising a pair of normally closed contacts 6l and 62 and a pair of normally open contacts 63-64, the contacts 61 and 64 being secured to the moveable member 58. When the fuze is in an armed condition, a tiring circuit is established from the firing mechanism 65 of any well-known type suitable for the purpose to the electroresponsive detonator 68 by way of conductor 69, contacts 63 and 64, and conductor 71 to one side of the detonator, the other side of the detonator being connected to the firing mechanism by conductor 72. The fuze is maintained in a safe condition during handling and transportation by the detent 46 and latch 49 and also by the circuit arrangement whereby the electroresponsive detonator 68 is normally short circuited by contacts 61-62, Fig. 3.

By the foregoing arrangement it will be understood that a firing circuit will not be established from the firing mechanism to the electroresponsive detonator until the bellows has been expanded or lengthened in the aforesaid manner, thereby moving the member 58 sufficiently to engage contacts 63-64 and to disengage contacts 61-62. It will be understood, however, that movement of the detent 46 will not occur until the bellows 53 has extended a sufficient distance to disengage the latch member 49 therefrom and thus complete arming of the fuze will not occur until the shell thereof toward a target.

has cleared the muzzle of the gun and` traveledl apredetermined distance therebeyond suicient to cause the uid within the bellows to spin at a rate at which the member 58 is moved thereby to an armed position.

The lag in the spin of the fluid with respect to the spin of the projectile and the delay in arming caused thereby will `best be understood by reference to Fig. 4 on which it is shown by the curve 75 the rate of spin of the projectile asthe projectile is fired from the gun and travels along a trajectory. The rate of spin of the huid within the bellows 53 is shown by the curve 76. The acceleration 0f the fluid from a state of rest to the rate of spin corresponding to the spin of the projectile requires a much longer period of time to achieve than the time required for the shell to reach a state of maximum rate of spin. The dash line 77 is employed to indicate the rate of spin of the fluid required to generate centrifugal force sufficient to extend the expansible bellows to the armed position thereof. The intersection of the dash line 77 with the curve 76 at point 78 occurs at a time T sufficient for the projectile to be well clear of the gun before the bellows is extended sufciently for contacts 61-62 to be disengaged and contacts 63--64 to be brought into engagement and thereby close the firing circuit from the firing mechanism to the detonator 68.

From the foregoing it will be apparent that the firing mechanism and the circuit arrangement therefor is particularly adapted to function the fuze electrically when the projectile strikes the target a glancing blow, and

"the firing pin 44 is adapted to function the fuze mechanically when the projectile strikes the target a head-onblow. Furthermore, by the aforesaid arrangement means are provided for delaying the arming of the fuze thereby to prevent explosion of the shell within the muzzle of the gun, such means being adapted to function thefuze and explode the shell regardless of the angle at which the shell strikes the target.

Whereas the invention in accordance with a preferred embodiment thereof has been described with particular reference to arming a projectile electrically by actuating electrical contacts as the bellows expands longitudinally, it is not so limited as, if desired, the bellows may be employed to cause motion in a mechanical arming system sufficient to move the components thereof into armed position as the bellows expands in response to the centrifugal force of the liquid sealed therein when the speed of rotation of the liquid reaches a predetermined value during the ight of the missile without departing from the spirit or scope of the invention. Furthermore, the elastic properties of the bellows may be supplemented by restraining springs or the like for additionally retarding movement of the bellows to the extended position thereof and, if desired, the bellows may be encased within a sleeve of suicient size to allow free longitudinal movement thereof but sufficiently close fitting to prevent bursting of the bellows in response to the pressure of the liquid therein as the liquid is spun during the flight of the projectile.

Whereas the invention has been described in detail with respect to a projectile, it will be understood, that it may be advantageously employed, if desired, with a spin rocket or other missile which rotates during travel While the device has been shown and described with electrical safety firing and arming means, it will be understood, that if desired, any

`electrical means may be employed with the bellows arrangement for maintaining the fuze in a safe condition until the missile has been fired from a gun and to delay the arming of the fuze until the missile has traveled a predetermined distance therefrom, in which means are provided for tiring the explosive within the missile upon impact of the missile with the target.

Obviously many modifications and variations of the charge.

present invention are possible in the lightl of the above teachings. It is therefore to be understood that within the scope of the appended caims the invention may be practiced otherwise than specically described.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed as new and desired to be secured by Letters Patent is:

1. In an impact fuze for a spin missile, a casing, an explosive charge arranged within said casing, an extensible bellows arranged within said fuze in coincidence with the axis of spin of the missile, respective end walls sealing said bellows, a quantity of liquid sealed within the bellows whereby said bellows is extended in response to the pressure of the liquid caused by centrifugal force of the liquid as the spin of the liquid approaches the spin of the missile, means actuated by an end wall of the bellows for arming the fuze when the 1bellows has been extended a predetermined amount, and means responsive to impact of the missile with a target for firing said explosive 2. In an impact fuze for a spin missile, a casing, an explosive charge arranged within said casing, an extensible bellows arranged within the fuze in coincidence with the axis of spin of the missile, respective walls sealing said bellows, a quantity of liquid sealed within the bellows whereby said bellows is extended in response to the pressure of the liquid caused by centrifugal force as the spin of the liquid approaches the spin of the missile, means including a latch member in engagement with an end wall of the bellows and operated thereby as the bellows is extended for arming the fuze, and means responsive to impact of the missile with a target for firing said explosive charge.

3. In an impact fuze for a spin missile, a casing, an explosive charge arranged within said casing, an extensible bellows arranged within said fuze with the axis thereof in coincidence with the axis of the missile, respective end walls sealing said bellows, a quantity of liquid sealed within the bellows whereby said bellows is extended axially in response to the pressure of the liquid caused by centrifugal force as the spin of the liquid approaches the spin of the missile for moving the bellows longitudinally within the fuze, means including a detent slideably arranged within the fuze for initially maintain- CTl 6 ing the fuze in -an unarmed condition and constructed and arranged to arm the fuze when moved a predetermined amount, means for releasing said detent in response to the movement of an end wall of said bellows, and means responsive to the impact of the missile with a target for ring said explosive charge.

4. In fuze for a spin missile, a casing, an explosive charge arranged within lsaid casing, an extensible bellows arranged within said fuze with the axis thereof in coincidence with the axis of the missile, end walls sealing the ends of the bellows, a quantity of liquid sealed within the bellows whereby said bellows is extended in response to the pressure of the liquid caused by centrifugal force as the spin of the liquid approaches the spin of the missile, a normally open firing circuit arranged within the fuze, means responsive to movement of an end wall of said bellows for closing the tiring circuit, a firing device arranged within said circuit for generating an electrical firing impulse, and an electroresponsive detonator included within the firing circuit and adapted to be fired in response to said electrical impulse.

5. In a fuze for a spin missile, a casing, an explosive charge arranged within said casing, an extensible bellows arranged within said fuze with the axis thereof in coincidence with the axis of the missile, respective end walls sealing the ends of the bellows, a quantity of liquid sealed within the bellows whereby said bellows is extended in response to the pressure of the liquid caused by centrifugal force of theliquid as the spin of the liquid approaches the spin of the missile, a normally open firing circuit A'arranged within the fuze, means responsive to movement of an end wall of said bellows for closing the ring circuit, a ring device arranged within said circuit for generating an electrical tiring impulse, an electroresponsive detonator included within the firing circuit and adapted to be red in response to said electrical impulse, and means on said bellows for normally short circuiting the detonator until the bellows has been moved longitudinally.

References Cited in the file of this patent UNITED STATES PATENTS 1,689,470 Adelman Oct. 30, 1928 2,110,552 Hayden Mar. 8, 1938 2,331,633 Spooner Oct. 12, 1943 2,404,553 Wales July 23, 1946 2,455,958 Taylor Dec. 14, 1948 

